Measurement of rotor blade flapping

RELATED APPLICATIONS

Pursuant to 35 U.S.C. § 119 (e), this application claims priority to U.S. Provisional Patent Application Ser. No. 61/753,256, entitled MEASUREMENT OF ROTOR BLADE FLAPPING, filed Jan. 16, 2013. U.S. Provisional Patent Application Ser. No. 61/753,256 is hereby incorporated by reference.

TECHNICAL FIELD

This invention relates generally to rotor systems, and more particularly, to measurement of rotor blade flapping.

BACKGROUND

A rotorcraft may include one or more rotor systems. One example of a rotorcraft rotor system is a main rotor system. A main rotor system may generate aerodynamic lift to support the weight of the rotorcraft in flight and thrust to counteract aerodynamic drag and move the rotorcraft in forward flight. Another example of a rotorcraft rotor system is a tail rotor system. A tail rotor system may generate thrust in the same direction as the main rotor system's rotation to counter the torque effect created by the main rotor system. A rotor system may include one or more pitch links to rotate, deflect, and/or adjust rotor blades.

SUMMARY

Particular embodiments of the present disclosure may provide one or more technical advantages. A technical advantage of one embodiment may include the capability to measure flapping of a rotor blade. A technical advantage of one embodiment may include the capability to improve flapping measurement accuracy. A technical advantage of one embodiment may include the capability to provide time-stamped measurements of rotor blade flapping. A technical advantage of one embodiment may include the capability to correlate rotor blade flapping measurements with blade rotation position.

Certain embodiments of the present disclosure may include some, all, or none of the above advantages. One or more other technical advantages may be readily apparent to those skilled in the art from the figures, descriptions, and claims included herein.

BRIEF DESCRIPTION OF THE DRAWINGS

To provide a more complete understanding of the present invention and the features and advantages thereof, reference is made to the following description taken in conjunction with the accompanying drawings, in which:

<figref idref="DRAWINGS">FIG. 1</figref> shows a rotorcraft according to one example embodiment;

<figref idref="DRAWINGS">FIG. 2</figref> shows a mechanical flapping measurement system installed on the rotor system of <figref idref="DRAWINGS">FIG. 1</figref> according to one example embodiment;

<figref idref="DRAWINGS">FIG. 3</figref> shows a flapping sensor system that may measure flapping of a blade of the rotorcraft of <figref idref="DRAWINGS">FIG. 1</figref> according to one example embodiment; and

<figref idref="DRAWINGS">FIG. 4</figref> shows a flapping measurement system featuring several of the flapping sensor systems of <figref idref="DRAWINGS">FIG. 3</figref> according to one example embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS

<figref idref="DRAWINGS">FIG. 1</figref> shows a rotorcraft <b>100</b> according to one example embodiment. Rotorcraft <b>100</b> features a rotor system <b>110</b>, blades <b>120</b>, a fuselage <b>130</b>, a landing gear <b>140</b>, and an empennage <b>150</b>. Rotor system <b>110</b> may rotate blades <b>120</b>. Rotor system <b>110</b> may include a control system for selectively controlling the pitch of each blade <b>120</b> in order to selectively control direction, thrust, and lift of rotorcraft <b>100</b>. Fuselage <b>130</b> represents the body of rotorcraft <b>100</b> and may be coupled to rotor system <b>110</b> such that rotor system <b>110</b> and blades <b>120</b> may move fuselage <b>130</b> through the air. Landing gear <b>140</b> supports rotorcraft <b>100</b> when rotorcraft <b>100</b> is landing and/or when rotorcraft <b>100</b> is at rest on the ground. Empennage <b>150</b> represents the tail section of the aircraft and features components of a rotor system <b>110</b> and blades <b>120</b>′. Blades <b>120</b>′ may provide thrust in the same direction as the rotation of blades <b>120</b> so as to counter the torque effect created by rotor system <b>110</b> and blades <b>120</b>. Teachings of certain embodiments relating to rotor systems described herein may apply to rotor system <b>110</b> and/or other rotor systems, such as other tilt rotor and helicopter rotor systems. It should also be appreciated that teachings from rotorcraft <b>100</b> may apply to aircraft other than rotorcraft, such as airplanes and unmanned aircraft, to name a few examples.

<figref idref="DRAWINGS">FIG. 2</figref> shows the rotor system <b>110</b> of <figref idref="DRAWINGS">FIG. 1</figref> according to one example embodiment. In the example of <figref idref="DRAWINGS">FIG. 2</figref>, rotor system <b>110</b> features a shaft <b>112</b>, a hub, <b>114</b>, and a pin <b>116</b>. Hub <b>114</b> and pins <b>116</b> may couple blades <b>120</b> to shaft <b>112</b>. In some examples, rotor system <b>110</b> may include more or fewer components. For example, <figref idref="DRAWINGS">FIG. 2</figref> does not show components such as a power train, a gearbox, a swash plate, grips, drive links, drive levers, and other components that may be incorporated.

The power train, shaft <b>112</b>, and hub <b>114</b> may represent examples of mechanical components for generating and transmitting torque and rotation. The power train may include a variety of components, including an engine, a transmission, and differentials. In operation, shaft <b>112</b> receives torque or rotational energy from the power train and rotates hub <b>114</b> about rotor axis <b>112</b><i>a</i>. Blades <b>120</b> are coupled to hub <b>114</b> by pins <b>116</b>. Rotation of hub <b>114</b> causes blades <b>120</b> to rotate about shaft <b>112</b>.

Blades <b>120</b> may be subject to a variety of different forces. For example, rotation of blades <b>120</b> may result in a centrifugal (CF) force against grips blades <b>120</b> in a direction away from shaft <b>112</b>. In addition, the weight of blades <b>120</b> may result in a transverse force being applied against hub <b>114</b>. These and other forces may cause blades <b>120</b> to feather, drag (also known as lead/lag), and flap during operation of rotorcraft <b>100</b>. The remainder of the discussion below will primarily focus on blade flapping.

Blade flapping may generally refer to up-and-down motion of a rotor blade during operation. In the example of <figref idref="DRAWINGS">FIG. 2</figref>, blade <b>120</b> is shown at a zero-degree flapping angle. In this example, blade <b>120</b> is centered on flapping-plane centerline <b>120</b><i>a</i>. When flapping occurs, blade <b>120</b> deviates upwards or downwards from flapping-plane centerline <b>120</b><i>a</i>, resulting in a flapping angle between flapping-plane centerline <b>120</b><i>a </i>and the flapping-plane of the blade.

Blade flapping may be caused by the changing speeds of a rotor blade during one rotation. For a single-rotor aircraft, the rotor disc may be divided into two sides: the advancing blade side and the retreating blade side. On the advancing blade side, rotation of the rotor blade causes the rotor blade to move in the same direction as forward flight of the aircraft. On the retreating side, rotation of the rotor blade causes the rotor blade to move in the opposite direction of forward flight of the aircraft.

An advancing blade, upon meeting the progressively higher airspeeds brought about by the addition of forward flight velocity to the rotational airspeed of the rotor, respond to the increase of speed by producing more lift. This increased production of lift causes the blade to flap (or lift) upwards. For a retreating blade, the opposite is true. The retreating blade responds to the progressively lower airspeeds by producing less lift. This decreased production of lift causes the blade to flap downwards.

In some examples, blade flapping may help compensate for dissymmetry of lift. Dissymmetry of lift may refer to an uneven amount of lift on opposite sides of a rotor disc. Blade flapping may compensate for dissymmetry of lift by decreasing the relative angle of attack of an advancing blade and increasing the relative angle of attack of a retreating blade.

Thus, some rotor systems may be designed to allow some rotor blade flapping. For example, a fully-articulated rotor system may include horizontal hinges that allow rotor blades to flap during operation. Excess flapping, however, may cause damage to the rotor system if the flapping angle exceeds recommended limits. Accordingly, teachings of certain embodiments recognize the capability to measure flapping of a rotor blade during operation of the aircraft. In addition, the magnitude of such damage may be a function of time or number of rotations (even a small increase in flapping angle can cause damage if the increased flapping angle is sustained over a long duration or a high number of rotations). Accordingly, teachings of certain embodiments recognize the capability to time-stamp or rotation-stamp rotor blade flapping measurements. Furthermore, rotor system inertia may result in a phase delay between maximum advancing blade speed (which one would expect to occur when the rotor blade is positioned perpendicular to the body of the aircraft) and maximum flapping angle (which one would expect to occur at some point after maximum advancing blade speed is reached). Accordingly, teachings of certain embodiments recognize the capability to correlate rotor blade flapping measurements with blade rotation position, which may allow for calculation of the phase delay and other aspects of rotor blade flapping.

<figref idref="DRAWINGS">FIG. 2</figref> shows a mechanical flapping measurement system <b>200</b> installed on rotor system <b>110</b> according to one example embodiment. Flapping measurement system <b>200</b> features a measurement system <b>210</b> and a linkage assembly <b>220</b>. Linkage assembly <b>220</b> couples measurement system <b>210</b> to hub <b>114</b> such that measurement system <b>210</b> may measure flapping of blade <b>120</b> by measuring movement of hub <b>114</b> as a result of blade flapping.

In the example of <figref idref="DRAWINGS">FIG. 2</figref>, measurement system <b>210</b> features a shaft <b>212</b>, a rotary variable differential transformer (RVDT) <b>214</b>, and a platform <b>216</b>. An RVDT is a type of electrical transformer operable to measure angular displacement. Platform <b>216</b> supports RVDT <b>214</b> and couples RVDT <b>214</b> to shaft <b>112</b>. Also in the example of <figref idref="DRAWINGS">FIG. 2</figref>, linkage system <b>220</b> features a linkage <b>222</b> and pivot bearings <b>224</b> and <b>226</b>. Pivot bearing <b>224</b> couples linkage <b>222</b> to shaft <b>212</b>, and pivot bearing <b>226</b> couples linkage <b>222</b> to hub <b>114</b>.

During operation, according to one example embodiment, flapping of blade <b>120</b> causes upward or downward movement of hub <b>114</b>. Upward or downward movement of hub <b>114</b> causes linkage <b>222</b> to move the tip of shaft <b>212</b> upward or downward. Moving the tip of shaft <b>212</b> increases or decreases angle <b>218</b>, which may be measured by RVDT <b>214</b>. In some embodiments, a nominal angle <b>218</b> may be defined for a zero-flapping position of blade <b>120</b>, and the flapping angle of blade <b>120</b> may be measured by reference to the nominal angle.

Although the mechanical flapping measurement system <b>200</b> of <figref idref="DRAWINGS">FIG. 2</figref> can provide a measurement indicative of rotor blade flapping, system <b>200</b> may be prone to a variety of measurement errors. For example, RVDT <b>214</b> is configured in system <b>200</b> to rotate with shaft <b>112</b> during operation, but rotating RVDT <b>214</b> can cause electrical phase shifts that affect signal demodulation. In addition, system <b>200</b> may be prone to errors caused by mechanical misalignments, mechanical crosstalk affecting the lateral and longitudinal sensor sample positions, and rotor hub compression. As one example, system <b>200</b> may be prone to measurement errors due to the offset <b>228</b> between the flapping plane of blade <b>228</b> and pivot bearing <b>226</b>. In the example of <figref idref="DRAWINGS">FIG. 2</figref>, system <b>200</b> does not directly measure flapping of blade <b>120</b>; rather, system <b>200</b> attempts to measure movement of hub <b>114</b> at pivot bearing <b>226</b> and then estimate flapping of blade <b>120</b> based on movement of pivot bearing <b>226</b>.

Furthermore, measurements provided by system <b>200</b> may be of limited value. For example, system <b>200</b> as shown in <figref idref="DRAWINGS">FIG. 2</figref> does not include mechanisms for time stamping or for correlating measurements with blade rotation position. Thus, even if system <b>200</b> could accurately measure blade flapping angle, for example, system <b>200</b> may not be able to calculate blade flapping velocities, accelerations, or phase shifts.

As will be explained in greater detail below, teachings of certain embodiments recognize the capability to eliminate or reduce inaccuracies due to mechanical linkages and electrical phase shifts by providing a position sensor in the rotor blade. For example, providing a position sensor, such as a microelectromechanical system (MEMS) position sensor, in a rotor blade, such as on the flapping plane of the rotor blade, may reduce or eliminate mechanical and electrical errors. Furthermore, teachings of certain embodiments recognize the capability to provide time stamping and/or blade rotation position information with flapping measurements.

<figref idref="DRAWINGS">FIG. 3</figref> shows a flapping sensor system <b>300</b> according to one example embodiment. Flapping sensor system <b>300</b> features a position sensor <b>310</b>, a measurement engine <b>320</b>, an index detector <b>330</b>, and a transceiver <b>340</b>.

Position sensor <b>310</b> provides measurements of identifying locations of position sensor <b>310</b> over time. As seen in the example of <figref idref="DRAWINGS">FIG. 2</figref>, position sensor <b>310</b> may be located on the flapping plane of the blade such that position sensor <b>310</b> provides measurements identifying the locations of the flapping plane of the blade over time. In some embodiments, position sensor <b>310</b> may provide location measurements in three dimensions, such as along the flapping axis (X), the rotational axis (Y), and the gravitational axis (Z). Movement in the X and Y axis may be seen in the example of <figref idref="DRAWINGS">FIG. 2</figref>. In some embodiments, position sensor <b>310</b> is operable to provide velocity and acceleration information as well as position information. This velocity and acceleration information may be used, for example, to determine flapping velocity and acceleration as well as correlate such measurements to blade velocity and acceleration. For example, the phase delay between maximum advancing blade speed and maximum flapping angle, as well as other information, may be determined from the position, velocity, and acceleration measurements provided by position sensor <b>310</b>.

In some embodiments, position sensor <b>310</b> is a MEMS device. MEMS is a technology associated with very small devices, merging at the nano-scale into nanoelectromechanical systems (NEMS) and nanotechnology. MEMS may also be referred to as micromachines. In some embodiments, MEMS devices may generally range in size from 20 micrometers to one millimeter and may be made up of components between 1 and 100 micrometers in size. Teachings of certain embodiments recognize that devices such as MEMS devices may be directly secured to/on a rotor blade without affecting weight, balance, and other performance characteristics of the rotor blade.

Measurement engine <b>320</b> may identify flapping based on measurements provided by position sensor <b>310</b>. In some embodiments, measurement engine <b>320</b> may identify flapping based on a comparison of the received measurements from position sensor <b>310</b> to a known zero-flapping index position of a rotor blade. The zero-flapping index position of a rotor blade may represent what the position measurements from position sensor <b>310</b> should be when the rotor blade is at zero-degree flapping angle. A blade <b>120</b> may be at zero-degree flapping angle, for example, when blade <b>120</b> is centered on flapping-plane centerline <b>120</b><i>a</i>, which may lie on the zero-flapping plane of blade <b>120</b>.

Measurement engine <b>320</b> may identify flapping of a rotor blade based on differences between measurements provided by position sensor <b>310</b> and the zero-flapping index position of the rotor blade. For example, measurement engine <b>320</b> may calculate a flapping angle of the rotor blade based on the comparison. For example, measurement engine <b>320</b> may calculate the flapping angle by comparing three-dimension position measurements form position sensor <b>310</b> to a zero-flapping coordinate system, which may be at least partially defined by the zero-flapping plane and/or the flapping-plane centerline <b>120</b><i>a </i>of blade <b>120</b>.

Index detector <b>330</b> may provide a variety of different indexing information. In one example embodiment, index detector <b>330</b> may provide information regarding the zero-flapping index position of a rotor blade. For example, index detector <b>330</b> may include a monopole sensor that detects when the rotor blade is at zero-degrees flapping. In this example, measurement engine <b>320</b> may determine a zero-flapping index position based on the position measurements provided by position sensor <b>310</b> corresponding to times when index detector <b>330</b> determines that the rotor blade is at zero-degrees flapping. Measurement engine <b>320</b> may then determine rotor blade flapping angles by comparing measurements provided by position sensor <b>310</b> to the determined zero-flapping index position.

In another example embodiment, index detector <b>330</b> may provide information regarding the blade rotation position of a rotor blade. For example, in one embodiment, index detector <b>330</b> may include a monopole sensor that detects when the rotor blade is at a fixed zero-degree rotor blade position. For example, the monopole sensor may be mounted on the rotating portion of rotor system <b>110</b> (such as shaft <b>112</b> or another rotating component) and identify every time the rotating portion passes a fixed, stationary position on rotorcraft <b>100</b> corresponding to the fixed zero-degree rotor blade position. Alternatively, as another example, the monopole sensor may be located at the stationary position and detect every time a certain part of the rotation portion passes.

In these examples, index detector <b>330</b> may provide time-stamped information identifying when the rotor blade is at the fixed zero-degree rotor blade position. This fixed zero-degree rotor blade position may represent a known location, such as a position directly over the nose of the aircraft, directly over the tail of the aircraft, or any known points in between. Measurement engine <b>320</b> may correlate this time-stamped information from index detector <b>330</b> with time-stamped measurements provided by position sensor <b>310</b>. Measurement engine <b>320</b> may identify, for example, measurements from position sensor <b>310</b> corresponding to when the rotor blade is located at the fixed zero-degree rotor blade position. In addition, measurement engine <b>320</b> may identify measurements from position sensor <b>310</b> corresponding to other blade rotation positions. For example, measurement engine <b>320</b> may estimate other blade rotation positions based on the amount of time elapsed between when the rotor blade passes the fixed zero-degree rotor blade position. As another example, measurement engine <b>320</b> may estimate other blade rotation positions using velocity and acceleration information provided by position sensor <b>310</b>.

In some embodiments, index detector <b>330</b> may feature multiple monopole sensors (or other sensors) to provide more accurate blade rotation position information. Accurate blade rotation position information may allow measurement engine <b>320</b> to determine, for example, lead-lag of the rotor blade by comparing differences between rotor shaft position (as determined by index detector <b>330</b>) and rotor blade position (as determined by position sensor <b>310</b>).

Accordingly, teachings of certain embodiments recognize that position sensor <b>310</b> and index detector <b>330</b> may allow measurement engine <b>320</b> to provide a variety of outputs. For example, in some embodiments, measurement engine <b>320</b> may provide a time-stamped flapping log for a rotor blade. This time-stamped flapping log may include, for example, the rotor blade flapping angle, flapping velocity, flapping acceleration, and blade rotation position of the rotor blade at each time entry. Measurement engine <b>320</b> may provide this and other output through a transceiver <b>340</b>.

<figref idref="DRAWINGS">FIG. 4</figref> shows a flapping measurement system <b>400</b> according to one example embodiment. Flapping measurement system <b>400</b> features multiple flapping sensor systems <b>300</b> in communication with a base processing sensor <b>410</b>, all or some of which may be implemented by one or more computer systems <b>10</b> and all or some of which may be accessed by a user <b>5</b>.

In some embodiments, each flapping sensor system <b>300</b> may be associated with one rotor blade, and the base processing sensor <b>410</b> may be associated with one rotorcraft. All, some, or none of the components of system <b>400</b> may be located on or near an aircraft such as rotorcraft <b>100</b>. For example, in one example embodiment, flapping sensor systems <b>300</b> may be located in the rotating portion of rotorcraft <b>100</b> (e.g., the rotating portion of rotor system <b>110</b>), and base processing sensor <b>410</b> may be located on the stationary portion of rotorcraft <b>100</b>. In this example, flapping sensor systems <b>300</b> may be separated from base processing sensor <b>410</b> by a slip ring and may communicate with base processing sensor <b>410</b> using an aircraft rotor interconnect.

In the example of <figref idref="DRAWINGS">FIG. 4</figref>, base processing sensor <b>410</b> features a transceiver <b>412</b>, a measurement engine <b>414</b>, a position sensor <b>416</b>, and an interface <b>418</b>.

Transceiver <b>412</b> may receive measurements from flapping sensor systems <b>300</b>. In some embodiments, transceiver <b>412</b> may include a multi-channel transceiver for receiving measurements from multiple flapping sensor systems <b>300</b>. In addition, transceiver <b>412</b> may include a power distribution system for powering flapping sensor systems <b>300</b>.

Measurement engine <b>414</b> receives and processes measurements from flapping sensor systems <b>300</b>. In one example embodiment, measurement engine <b>414</b> adjusts the received measurements based on data provided by position sensor <b>416</b>. Position sensor <b>416</b> may provide position, velocity, acceleration, and other information about a fixed portion of rotorcraft <b>100</b>. In one example embodiment, position sensor <b>416</b> may be mounted in the nacelle of rotorcraft <b>100</b> (either together with or separate from other components of system <b>400</b>). Position sensor <b>416</b> may provide inertial reference information that allows sensor <b>400</b> to detect nacelle tilt and establish a platform reference for the measurements received from flapping sensor systems <b>300</b>.

Measurement engine <b>414</b> may transmit flapping and other data to devices on or off rotorcraft <b>100</b> using transceiver <b>418</b>. Transceiver <b>418</b> may transmit data, for example, to remote processing units such as flight control computers via a ARINC bus protocol or a serial data link. In some embodiments, measurement engine <b>414</b> may provide real-time warnings to the pilot that rotor blade flapping is too high (e.g., if rotor blade flapping angles, velocities, and/or accelerations exceed predetermined thresholds). In some embodiments, measurement engine <b>414</b> may transmit data to aircraft health monitoring systems that analyze health of the rotor blades, the rotor system, the airframe, and other rotorcraft components. The aircraft health monitoring systems may assess, for example, whether rotorcraft components should be replaced based on vibration data provided from measurement engine <b>414</b>.

As stated above, all or some of flapping sensor systems <b>300</b> and base processing sensor <b>410</b> may be implemented by one or more computer systems <b>10</b> and may be accessed by a user <b>5</b>. For example, in some embodiments, user <b>5</b> may access measurements provided by flapping sensor systems <b>300</b> and/or base processing sensor <b>410</b>. As another example, user <b>5</b> may program, modify, and/or upgrade flapping systems <b>300</b> and/or base processing sensor <b>418</b> through computer systems <b>10</b> and/or network <b>30</b>.

Examples of users <b>5</b> include, but are not limited to, a pilot, service person, engineer, technician, contractor, agent, and/or employee. Users <b>5</b> may be associated with an organization. An organization may include any social arrangement that pursues collective goals. One example of an organization is a business. A business is an organization designed to provide goods or services, or both, to consumers, governmental entities, and/or other businesses.

Computer system <b>10</b> may include processors <b>12</b>, input/output devices <b>14</b>, communications links <b>16</b>, and memory <b>18</b>. In other embodiments, computer system <b>10</b> may include more, less, or other components. Computer system <b>10</b> may be operable to perform one or more operations of various embodiments. Although the embodiment shown provides one example of computer system <b>10</b> that may be used with other embodiments, such other embodiments may utilize computers other than computer system <b>10</b>. Additionally, embodiments may also employ multiple computer systems <b>10</b> or other computers networked together in one or more public and/or private computer networks, such as one or more networks <b>30</b>.

Processors <b>12</b> represent devices operable to execute logic contained within a medium. Examples of processor <b>12</b> include one or more microprocessors, one or more applications, and/or other logic. Computer system <b>10</b> may include one or multiple processors <b>12</b>.

Input/output devices <b>14</b> may include any device or interface operable to enable communication between computer system <b>10</b> and external components, including communication with a user or another system. Example input/output devices <b>14</b> may include, but are not limited to, a mouse, keyboard, display, and printer.

Network interfaces <b>16</b> are operable to facilitate communication between computer system <b>10</b> and another element of a network, such as other computer systems <b>10</b>. Network interfaces <b>16</b> may connect to any number and combination of wireline and/or wireless networks suitable for data transmission, including transmission of communications. Network interfaces <b>16</b> may, for example, communicate audio and/or video signals, messages, internet protocol packets, frame relay frames, asynchronous transfer mode cells, and/or other suitable data between network addresses. Network interfaces <b>16</b> connect to a computer network or a variety of other communicative platforms including, but not limited to, a public switched telephone network (PSTN); a public or private data network; one or more intranets; a local area network (LAN); a metropolitan area network (MAN); a wide area network (WAN); a wireline or wireless network; a local, regional, or global communication network; an optical network; a satellite network; a cellular network; an enterprise intranet; all or a portion of the Internet; other suitable network interfaces; or any combination of the preceding.

Memory <b>18</b> represents any suitable storage mechanism and may store any data for use by computer system <b>10</b>. Memory <b>18</b> may comprise one or more tangible, computer-readable, and/or computer-executable storage medium. Examples of memory <b>18</b> include computer memory (for example, Random Access Memory (RAM) or Read Only Memory (ROM)), mass storage media (for example, a hard disk), removable storage media (for example, a Compact Disk (CD) or a Digital Video Disk (DVD)), database and/or network storage (for example, a server), and/or other computer-readable medium.

In some embodiments, memory <b>18</b> stores logic <b>20</b>. Logic <b>20</b> facilitates operation of computer system <b>10</b>. Logic <b>20</b> may include hardware, software, and/or other logic. Logic <b>20</b> may be encoded in one or more tangible, non-transitory media and may perform operations when executed by a computer. Logic <b>20</b> may include a computer program, software, computer executable instructions, and/or instructions capable of being executed by computer system <b>10</b>. Example logic <b>20</b> may include any of the well-known OS2, UNIX, Mac-OS, Linux, and Windows Operating Systems or other operating systems. In particular embodiments, the operations of the embodiments may be performed by one or more computer readable media storing, embodied with, and/or encoded with a computer program and/or having a stored and/or an encoded computer program. Logic <b>20</b> may also be embedded within any other suitable medium without departing from the scope of the invention.

Various communications between computers <b>10</b> or components of computers <b>10</b> may occur across a network, such as network <b>30</b>. Network <b>30</b> may represent any number and combination of wireline and/or wireless networks suitable for data transmission. Network <b>30</b> may, for example, communicate internet protocol packets, frame relay frames, asynchronous transfer mode cells, and/or other suitable data between network addresses. Network <b>30</b> may include a public or private data network; one or more intranets; a local area network (LAN); a metropolitan area network (MAN); a wide area network (WAN); a wireline or wireless network; a local, regional, or global communication network; an optical network; a satellite network; a cellular network; an enterprise intranet; all or a portion of the Internet; other suitable communication links; or any combination of the preceding. Although the illustrated embodiment shows one network <b>30</b>, teachings of certain embodiments recognize that more or fewer networks may be used and that not all elements may communicate via a network. Teachings of certain embodiments also recognize that communications over a network is one example of a mechanism for communicating between parties, and any suitable mechanism may be used.

Modifications, additions, or omissions may be made to the systems and apparatuses described herein without departing from the scope of the invention. The components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses may be performed by more, fewer, or other components. The methods may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order.

Although several embodiments have been illustrated and described in detail, it will be recognized that substitutions and alterations are possible without departing from the spirit and scope of the present invention, as defined by the appended claims.

To aid the Patent Office, and any readers of any patent issued on this application in interpreting the claims appended hereto, applicants wish to note that they do not intend any of the appended claims to invoke paragraph 6 of 35 U.S.C. §112 as it exists on the date of filing hereof unless the words “means for” or “step for” are explicitly used in the particular claim.